implicit

I am using a RightFolder that returns a Tuple2 and would like to return the _1 part. The first version rightFoldUntupled1 works fine but uses an additional IsComposite typeclass. In the second version rightFoldUntupled2 I try to achieve the same without IsComposite by destructuring P as a Product2[_, Values] . That doesn't work any more - the compiler is happy to witness that P is a Product2[_,_] , but as soon as I use a named type parameter for _1 it doesn't compile any more. Any idea why? The full source (with sbt ready to ~run with implicit debug output) is here: https://github.com

I would like to generate functions for a class accepting 1 type parameter case class C[T] (t: T) depending on the T type parameter. The functions I would like to generate are derived by the functions available on T . What I would like exactly, is to make all the functions available for T , also available for C . As an example for C[Int] , I would like to be able to call on C any function available on Int and dispatch the function call to the Int contained in C . val c1 = new C(1) assert(c1 + 1 == 2) How can I achieve this by using Scala 2 or dotty macros? Or, can this be achieved in another

To my mind the advantage of implicit localization over explicit localization is that if you have more than one property to localize for a given control, it's a more economical syntax. In the case where you just need to localize some text I use the asp:Localize control which only has a single property (Text) that renders to the UI. Is there a reason to use one over the other? Any style preference? Are there any speed differences? Implicit <asp:Localize ID="Localize1" runat="server" meta:resourcekey="Something" /> vs Explicit <asp:Localize ID="Localize1" runat="server" Text="<%$ Resources

I am trying to create a typeclass Default that supplies the default value for a given type. Here is what I have come up with so far: trait Default[A] { def value: A } object Default { def withValue[A](a: A) = new Default[A] { def value = a } def default[A : Default]: A = implicitly[Default[A]].value implicit val forBoolean = withValue(false) implicit def forNumeric[A : Numeric] = withValue(implicitly[Numeric[A]].zero) implicit val forChar = withValue(' ') implicit val forString = withValue("") implicit def forOption[A] = withValue(None : Option[A]) implicit def forAnyRef[A >: Null] = withValue

I never liked implicit operators (prefer extension methods) because it is hard to see visually when that cast/conversion happens in the code. Imagine if you have example like below: public static implicit operator Deal(string dealAsXml) { //convert the xml into Deal object } Above implicit operator helps you to cast/convert deal in Xml format into Deal Object. Usually when you right click on a method, you can use "Find Usages" (or Alt+F7) on it, which is quite helpful, is there anything similar for implicit operators ? I think that's another reason to use the Extensions methods where possible.

I need to pass two functions as parameters to a scala function. That function should then evaluate them and get a number from them where it will then operate on. This number can be either a Int, Double or any other numeric type. I would like the function to work, whatever the types it is working with. The example bellow explains the issue. import Numeric.Implicits._ class Arithmetic[T : Numeric](val A: Connector[T], val B: Connector[T]) { val sum = new Connector({ A.value + B.value }) } class Constant[T](var x: T) { val value = new Connector({ x }) } class Connector[T](f: => T) { def value: T

There is a declaration of template class with implicit parameters: List.h template <typename Item, const bool attribute = true> class List: public OList <item, attribute> { public: List() : OList<Item, attribute> () {} .... }; I tried to use the fllowing forward declaration in a different header file: Analysis.h template <typename T, const bool attribute = true> class List; But G++ shows this error: List.h:28: error: redefinition of default argument for `bool attribute' Analysis.h:43: error: original definition appeared here If I use the forward declaration without implicit parameters template